A pipe connection of the male and female type is known in which the female part is in the form of a sleeve connected with or unitarily formed on one of the two pipes to be connected, while an insert, which is generally cylindrical and tubular, is formed on the other pipe to constitute the male member which is insertable into the sleeve.
The sleeve can be provided with an inlet guide member forming the mouth of the sleeve, a final guide part or member axially inwardly of the sleeve and an enlargement between the guide members which forms a receiving channel accommodating a retaining ring.
A sealing chamber can be provided between the final guide member and the channel to accommodate a sealing lip which, in the absence of the insert part, extends frustoconically inwardly from the body of the ring. The sealing lip may have a gripping or closure lip formed thereon which conically widens away from the funnel-shaped sealing lip, i.e. axially inwardly.
The inner surface of the retaining ring can be formed with a compression rib which can define a ramp inclined toward the inlet guide member so that it is engaged by the insert part and can be pressed outwardly upon such insertion to seat the ring body firmly in the channel.
A pipe connection of this type is described in the German Patent 28 00 408. Pipe connections and pipe systems with such connections are utilized, for example, as subterranean conduits, especially to form cable-protecting tubing or as cable-guide tubing.
The pipe connections can be described as two-phase pipe connections because the arrangement of the sleeve structure and the retaining ring has a dual function. Firstly, the compression rib of the retaining ring provides upon insertion of the insert part, an initial centering of the insert part. Thereafter the sealing lip with the closure or gripping lip formed thereon, provides a sealing and gripping action. The earlier system required a relatively high insertion force and thus significant insertion effort to overcome the resistance to insertion of the insert part provided by the ring which, although, composed of rubber and thus elastically deformable, is substantially incompressible.
Of course the absolute value of the force required to fit the parts together and hence the insertion effort will depend upon the Shore hardness of the rubber.